Helserisiko ved PCB

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Helserisiko ved PCB

• Niklas Johansson
• Karolinska institutet
• och Naturvårdsverket

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What is PCB?

• Complex mixture of some 150 (of a total of 209)
  different congeners.
• These are resistant to break down
• Chemically related but show profound biological
  differences

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PCB 209 different congeners
orto-
Cl
para-
Cl
meta-
Cl
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The PCB story in Sweden

• 1966 Identified in the environment
• 1971 First legislation on PCB
• 1973 Use in open applications banned
• 1978 New use in closed applications
  
  
  banned
• 1988 Step wise reduction of use in closed
  systems
• 1995 All use banned

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PCB some important properties

• Resist high pressure and temperature
• Good electric inulator
• Not flammable at low temperatures
• Good stabilizing properties for polymers
• Resist biological and chemical degradation
  processes, but
• Can be bio-accumulated and bio-magnified and
  cauce severe chronic effects

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Consequences of high persistancy

• Will be present in the environment for decades or
  more
• Could be distributed not only locally but on a
  broad scale
• Eventually accumulated in certain compartments in
  the environment
• Exposure times will be long
• Actions and regulations will only slowly improve
  the environmental situation

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PCB-level in soil at different distances from the
building
mg/kg
Distance from facade (m)
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Dioxins and coplanar PCB in Guillemot
ng TEQ/g fat
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TEQ, toxic equivalency

• Some PCB (co-planar) act via the same mechanism
  as dioxins
• Their toxicity is however generally lover
  compared to dioxins
• By comparing the toxicity of different dioxins
  and PCBs with the most toxic dioxin, TCDD, a
  toxic equivalency factor, TEF, can be calculated
  for individual PCB and dioxin congeners
• Total dioxin toxicity (TEQ) can be calculated

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POPs in food, ng/kg b.w. and day
pg TEQ/kg b.w.and day
Vår föda, 2002, no 4
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PCB in different foodstuffs
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PCB in fish and shellfish in a normal diet
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Dioxins and PCB in fish from the Baltic proper,
pg/g fresh weight (1995)
Currnet EU-limit for fish 4 pg/g fresh weight
(contains so far dioxins only)
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Mean intake of dioxins and dioxin-like PCB
pg TEQ
Dayly intake 90-110 pg 1,3 pg/kg
b.w.
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Dioxins and PCB in breast milk Mixed samples from
Stockholm
TEQ pg/g fat
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Effects of PCB

• Low acute toxicity
• Skin
• Digestive system
• Lungs
• Nervous system
• Vitamin A homeostasis
• Effects on the liver
• Enzyme induktion

• Affect the immune system
• Reproductive disturbances
• aborts
• number of litters
• Behaviour effects
• Endocrine effects
• Cancer
• Etc. etc.

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How toxic isPCB?

• Some PCB show profound similarities with dioxins
  but they are less toxic than the dioxins.
• Other PCB act via different mechanisms (Reports
  on mental retardation in children from USA, is
  attributed the non dioxin-like PCB)

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Health risk assessment

• Based on dioxin-like effects only
• Tolerable Dayly Intake (TDI) of dioxins and
  dioxin-lika PCB 2 pg TEQ/kg b.w. (SCF, EU)
• TDI often exceeded in the general population,
  especially by breast fed children but also by
  fishermen and their families

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Livsmedelsverkets råd om konsumtion av fet fisk
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Livsmedelsverkets råd om konsumtion av fet fisk
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Conclusions

• Human exposure has decreased since 1970 but
  exposure is still unsatisfactory high
• Risk assessment based on dioxin-like effects only
• TDI is exceeded in segments of the general
  population
• Dietary recommendations still justified
• Urgent to stop further PCB leakage into the
  environment

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Is it dangerous to live in a PCB-house?

• We know that the levels in air could be
  substantially elevated
• Long exposure times
• Low chlorinated PCB
• Uptake probably high
• Few human studies on the relationship between
  exposure via indoor air and levels in blood
• Divergent results
• No panic

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Is it dangerous to live in a PCB-house?

• En studie av sambandet mellan PCB-halt i
  inomhusluft och och halt i blod startad
• Förstudie
• mätning av halt i luft visar tydliga skillnader
• Upp till 100 gånger högre totalhalter
• Medelvärden 0,005 0,35µg/m3
• Halterna dock väsentligt lägre än gränsvärde för
  arbetsmiljö (10 µg/m3)
• Lågklorerade PCBer

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PCB in Indoor and Outdoor Air (Relative Units)
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Loading plot of the second (p2) and third (p3)
principal components
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Is it dangerous to live in a PCB-house?

• Huvudstudie
• enkät för registrering av faktorer som kan
  påverka PCB-halt
• mätning av PCB-halt i blod
• Preliminära resultat pekar på att även halter i
  blod kan vara förhöjda
• Ingen säker skillnad för dioxinlika PCBer (med
  TEF)

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PCB levels in blood of residents (ng/g lipid)
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But